Studies on biological activity of wood extractives (V). Identification of flavonoids from the heartwood of Larix leptolepis and their antioxidative activities.

Two flavanones and one flavone were isolated from the diethylether soluble fraction of ethanol extract of Larix leptolepis heartwood. These compounds were identified 3,3',4',5,7-pentahydroxyflavanone(taxifolin), 3,4',5,7-tetrahydroxyflavanone(aromadendrin) and 3,3',4',5,7-pentahydroxyflavone(quercetin) by instrumental analyses using UV, IR, MS and NMR spectrometries. Antioxidative activies of these compounds were investigated by 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging activity. Quercetin and taxifolin indicated high free radical scavenging activities compared to -tocopherol and BHT(butylated hydroxytoluene).